Remote control for radio receivers



Feb 4 1936. c. E. BRUSH REMOTE CONTROL FOR RADIO RECEIVERS Filed sept.

5, 1931 2 Sheets-Sheet 1 ZEPODUCEY 5 ECOND Perec 7h72 INTERNE/A TE AMFL/F/ER Pon/57e SUPP/.k

LOCAL Inventoz CHESTER E BEUS/ mam C. E. BRUSH REMOTE CONTROL FOR RADIO RECEIVERS Filed Sept. 5, 1931 2 Sheets-Sheet 2 H M B E um 5 Cum. c

Patented Feb. 4, 1936 UNITED STATES QATENT OFFICE 2,029,461 RERIOTE CONTROL FOR RADIO RECEIVERS Chester E. Brush, Chicago, Ill., assignor to E. H. Scott Application September 5, 1931, Serial No. 561,430 4 Claims. (Cl. Z50-20) This invention relates to improvements in radio and which is portable within the range of a conbroadcasting receivers and more particularly renecting cable.

lates to means and methods for selectively con- Another object of the invention resides in the trolling reception in a receiver of the superprovision of a remote control wherein the num- 5 heterodyne type. ber of stations which may be selectively received, 5

Remote controls for radio receivers have but is limited only by the range of the receiver. recently attained the recognition of different Another object relates to the provision of a manufacturers. However, nearly all of the socontrol for a radio broadcast receiver wherein the called remote controls relate to a means for operation of selecting a broadcast station is exchanging the tuning control within the receiver tremely simpliied. l0 itself. This has been accomplished in many Other objects of the invention and the invenways, among the more prominent are, the protion itself will become more apparent from the vision of a motor which may be actuated from a following description of some embodiments of remote point to rotate or move the condensers the invention, in which description reference is increasing or decreasing capacities, or to move had to the accompanying drawings. 15

other tuning controls to a predetermined position In the drawings: whereby a certain station, which has been pre- Fig. l is a circuit diagram of a heterodyne reviously selected from a point within the radio ceiver equipped with both alocal and remote conbroadcast band, is tuned in. trol;

Nearly all of the known controls are subject to Fig. 2 is a diagrammatic view showing the allo- 20 certain inherent defects among which may be cation of the various units of this receiver and enumerated the addition of complicated mechatheir relation to each other;

nisms to accomplish the foregoing, and the fact Fig. 3 is a circuit diagram of a heterodyne rethat a slight shift in the allocation of a certain ceiver adapted to be controlled from a remote station in the broadcast wave band, necessitates point only; and 25 a complicated readjustment beyond the compre- Fig. 4 is a diagrammatic view showing the allohension of the average broadcast receiver audication of the parts of the receiver of Fig. 3 and ence. their relation to each other.

Further difficulties are presented in proper con- Fig. 5 is a plan view of a control switch.

SO trol of volume. What would be suiiicient volume Briefly. the invent-LOD aS illustrated in Figa 1 30 for a local station may be totally insufficient for and 2, includes a receiver of the superheterodyne the distance station and vice versa. type in which a local oscillator is built in the It is therefore among the objects of this invenreceiver; and a means for rendering the local ostion to provide a mechanism, which is simple to cillator inactive, connecting in a remote oscillator adjust and which will not readily lose its adjustin place thereof, and rendering the tuned stage 35 ment, whereby a predetermined broadcast station of the receiver untuned and responsive t0 Signals may be readily selected from a plurality of such throughout the broadcast band in such a manner stations from a point remote from the receiver. that by Varying Jthe frequency 0f the TemOte OS- Another object of this invention is to provide cillator the stations may be selectively received a control for instantaneously selecting stations through a beat ffeqllel'ley t0 Wheh the llleln 40 at the receiver without the necessity of going mediate amplifier and detector tube is responsive. through a number of stations to tune in the de- Referring mOre partelllarly to Fig. l, Jthe ansired station. tenna circuit may comprise the usual antenna 5 Another object of the invention resides in the With an antenna inductance 6 in series therewith.

provision of a control which is particularly adapt- An indue/Canela WhCh iS paralleled by a Ie- 45 able for superheterodynes and wherein the resistance 8 is in series between the inductance 6 ceiver may be controlled either at the receiver or and the ground. A Secondary radio frequency remotely therefrom. inductance 9 is coupled directly to the antenna Another object resides in providing a control for and may be tuned 130 I`eSODaI1Ce by a Variable 0aaradio receiver wherein the receiver may be conpaety |0- A TeSiStaIlCe 30 iS adapted t0 be 50 trolled only from a remote point. shunted across the capacity l0 by a single pole Another object of the invention is to provide a double throw Switch A, which switch is also remote control which not only selects the station adapted to short circuit the inductance and redesired, but wherein the volume may also be sistance 8. controlled at a point remote from the receiver An oscillator pickup coil H is interposed in 55 the grid circuit I3 of a screen grid tube I 2. An oscillator is inductively coupled to the pickup coil II, and includes a tube I4 having an inductance I5 in series with the plate circuit and an inductance I6 in series with the grid circuit. A fixed capacity I1 and a variable capacity I8 control the feed back between the plate and grid. The plate potential may be applied through a single pole single throw switch D.

The signal volume is controlled by variable resistance 20 in series between the ground and the cathode 2I; the radio frequency currents being bi-passed by a capacity 22. A single pole double throw switch B" is adapted to connect or disconnect the local volume control and the remote volume control.

In operation, with the control at the receiver wherein the local oscillator is used, the switch A is thrown in such a manner that the coil 'I and resistance 8 are shorted and the effective antenna circuit includes only the primary inductance 6.

The single throw switch D connects the positive screen of the first detector tube I 2 to the plate circuit of the oscillator tube I4 furnishing a plate potential for the oscillator, which as designated in the drawing may be 45 volts. The single pole double throw switch B closes the circuit between the cathode 2| and the local volume control 2U.

Signals collected by the antenna 5 pass through the inductance 6 and induce a current in the secondary 9. The secondary 9 is tuned to resonance at a particular wave length or kilocycle by a variable capacity IIJ, the signals are then communicated through the pickup coil II to the grid of the tube I2. The oscillator which is tuned by the variable capacity I8 between the plate and the grid generates an oscillatory current, the frequency of which is predetermined by the amount of the capacity I8, which induces an cscillatory signal in the pickup coil II and which is mixed with the incoming signal. This first radio frequency stage is commonly called the first detector. The output from the first stage which includes the received signal and the generated signal mixed to form a beat frequency is then conducted to an intermediate radio frequency amplifier 25. The radio frequency amplifier has been illustrated as including three stages of radio frequency amplification which are resonant to the beat frequency furnished by the received signal and the oscillator in the so-called first detector stage.

The beat frequency signal is amplified in the radio frequency amplifier, the output of which is connected to a detector 26 wherein the modulated beat note of radio frequency is rectified to audio frequency. The output of the detector may be connected to an audio frequency amplifier 21 the output of which is conducted to a reproducer 28.

When it is desired to control the receiver from a remote point, the switch A is thrown to the right as shown in the drawings wherein the resistance 30 is shunted across the capacity I0 and the secondary inductance 9. The switch A which had previously short circuited the inductance I and its parallel resistance 8 which are in series with the antenna coil 6 and the ground, is now open. The result of by-passing the tuned secondary 9 with the resistance 30, and the inductance 1 with the resistance 8, is to render the first stage, which was previously a tuned stage, an untuned stage, broad enough to be responsive to signals throughout the range of the broadcast band. The switch D is opened rendering the local oscillator ineffective.

The switch B is thrown to disconnect the local volume control from the cathode and connect the cathode to the conductor 3| which leads to a terminal 48 of a junction block or socket 32 for coupling the same to the remote control.

The single pole single throw switch E makes contact introducing positive B power from the line 33 through a radio frequency choke coil 34 which keeps radio frequency currents out of the B supply and which is also connected by the conductor 35 to the primary inductance coil 36 located in inductive relation with the secondary inductance coil 9 of the antenna circuit. The primary inductance coil 36 is connected to the ground through a blocking capacity 31. The

conductor 38 which connects to conductor 35 leads to a terminal 39 of the junction block 32. A terminal 4I of the junction block is grounded. The terminals 42 of the junction block are connected to the filament current supply not specifically shown.

The remote oscillator is coupled to the set by a plug 43 the conductors leading to the plug all being disposed in a fiexible cable 50. The plug is provided with prongs 42', 4I, 40', and

39 which are adapted to contact with the terminals 42 to 33 respectively, of the junction block 32 and provides an outlet for the necessary conductors essential to the operation of the remote control. The conductors contained in the fiexible cable 50, comprise the plate circuit wire 38', which connects to conductors 38 through pin and contact 39 and 39 respectively of plug and junction block, the filament wires 5I connect to filament contact 42, the volume control 68 connects to cathode wire 2I through conductor 3I and the ground 52 connects to the ground contact 4I.

The remote oscillator includes a vacuum tube having an inductance in the form of a tickler coil 6I disposed in the plate circuit; plate potential is provided through the conductor 38'. A primary inductance 62 is connected in the grid return circuit between the ground wire 52 and the grid 63. The filament of the tube is heated by current from the filament wires 5I.

The primary inductance is tuned by a fixed capacity 64, a plurality of semi-fixed capacities 65 and a trimmer variable capacity 66. The capacities 65 are adapted to be selectively connected into the circuit across the inductance 62 in series with the capacity 64 by a plurality of switches 61. A volume control connects the cathode of the receiver, through a variable resistance 68 to the ground wire 52.

In operation, a single control serves to simultaneously make or break the various portions of the circuit necessary to switch over to remote control, the local oscillator is rendered ineffective by opening the switch D; the first tuned stage is changed to an untuned stage by the single pole double throw switch A; the local volume control is rendered ineffective by the single pole double throw switch B which disconnects the local volume control and connects the remote volume control to make the same effective; the plate current is communicated to the remote oscillator by means of the switch E. The operation then will be substantially as follows:

Signals are picked up by the antenna 5 and are communicated into the first tube I2 through the coil I I from the untuned secondary 9.

Such a switch is illustrated in Fig. 5 wherein mote oscillator,

a control knob '|0'is provided which is adapted to actuate a cam element 204 extending between contact blades 200 and 20| which are the movable blades of the single pole double throw switches A and B. The movable blades of the switches are connected to the movable blades 205 and 206 of the single pole single throw switches D and E by insulated members 202 and 203. In the position shown the switches A, B, D and E are adapted to contact or be broken as previously described for tuning control at the receiver, in which position the local oscillator is connected through the switch D and the switch E is open, the local volume control connected and the antenna circuit is a tuned antenna circuit. When the knob is rotated the cam forces the blades outwardly shifting the switches A and B, opening the switch D and closing the switch E.

As previously described, the addition of the resistance across the capacity broadens the tuning of the first stage so that it is substantially untuned and responsive to an entire broadcast band. The remote oscillator generates an oscillatory current by means of the feed back from the tickler coil 6| into the primary coil 62 setting up an oscillatory signal in the oscillator, which signal is communicated through the plate circuit 38' and conductor 35 to the primary inductance 36, which is inductively coupled to the untuned secondary 9, and thence by-passed through the blocking condenser 31 to the ground.

The capacities 65 which tune the primary inductance B2 of the oscillator and which may be selectively connected into the circuit, are provided with a variable control in order that the capacity may be varied to generate the desired beating frequency in the oscillator and when once adjusted needs little or no attention thereafter.

The radio frequency energy from the oscillator which is conducted to the primary inductance coil 36 of the receiver mixes the locally generated signal with the incoming signals which are then impressed on the grid of the first tube I2 producing a beat note dependent upon the frequency of the local oscillator and on the received signal which beat note is of a frequency to which the intermediate frequency amplifier will select and amplify. The output of the first stage is then conducted to the intermediate frequency amplier in a manner similar to that previously described for the local oscillator operation.

A diagrammatic view of Fig. 2 illustrates, by the blocks, the aforedescribed circuit.

As previously stated the various switches are controlled by a single lever which throws the switch A, B and E in one direction to render the rstradio frequency stage tuned; the local volume control veffective and to render the local oscillator effective and when the lever is thrown in the opposite direction switch A renders the first radio frequency stage untuned, switch B uncouples the local volume control and couples the remote volume control; switch E uncouples the local oscillator and couples the rethis switch is indicated at 'l0 in Fig. 2 and may be of the so-called jack type.

The remote oscillator which includes the pri-- mary inductance, the tickler coil, volume control and the necessary capacities, as shown diagrammatically, are housed in the remote control box 1|; the switches 61 being actuated by buttons 61 and the trimmer capacity by a knob 66 and the volume control by a knob 68' substantially as shown.

The trimmer capacity merely serves to add or subtract a slight amount of capacity in the remote oscillator to more sharply tune stations which have slight variations sometimes due to climatic conditions or variations which may be in the receiver itself.

It is to be understood that although I have illustrated a control which selects the stations by tuning the oscillator by the introduction of predetermined capacities across the primary inductance, it can readily be seen by one skilled in the art, that the semi-fixed capacities might be replaced by single variable capacities and a single control dial provided in substantially the same manner as the changing of the capacity is accomplished directly Within the receiver.

It is also understood that the tuning of the oscillator might be varied by the introduction of inductances instead of capacities. The power supply is provided for within the receiver itself and the remote control receives its power through the cable 50 as previously described.

Referring now to Figs. 3 and 4, where I have illustrated by a circuit diagram and by the diagrammatic view, a receiver adapted to be operated from a remote point only which comprises Fig. 4, an untuned first stage 80, a remote oscillator 8| and an intermediate frequency amplifier 82, detector 83 and an audio frequency amplifier Sli. The antenna circuit consists of a primary inductance 85 and a secondary inductance 86, the secondary inductance is bridged by resistances B1 and 81'. One end of the secondary inductance is connected in the grid circuit 88 and the other end to the ground.

The remote oscillator 8| ondary inductance by a primary inductance 39 which is disposed in inductive relation thereto, beingconnected to the tickler coil 90 which is in the plate circuit of the oscillator, by a conductor 9|. The oscillator may be operated with a heater cathode type tube 92 and includes a primary inductance 93 in the grid circuit 02 tuned by capacities 04 and 05 in a similar manner to that described for the remote oscillator of the other embodiment. The plate current is supplied to the plate of the oscillator from the power supply through the conduit 90, a radio frequency choke coil 91 being interposed to stop the radio frequency currents from entering the power supply. The grid return connects to the cathode 00. Filament current is supplied through conductors S9.

The volume control comprising variable resistance |0| is connected to a conductor |52 to vary the amount of power supplied to the cathode of the tubes in the main receiver.

The conductors 9|, 90, |00 and 00 may all be disposed in a single iiexible covered cable. The operation of this embodiment is exactly the same as that of the previously described embodiment except it is operable through the remote control only. Either method of tuning the inductance in the oscillator may be used, such as the semi-fixed condensers and switches described for the other embodiment or the single tuning condenser operated by the usual dial.

Signals throughout an entire broadcast band are received by the detector 80. Oscillatory signals of a definite frequency are generated in the oscillator and mixed with the incoming signals to provide a beat frequency, to which the intermediate amplifier is resonant, after which the amplified signals are demodulated by the detector and then further amplified by a suitable audio amplifier, the output of the audio amis coupled to the secplifier being connected to a suitable reproducer. Power is supplied to the separate stages by power supply |05 which may be connected by a plug |03 to the local lighting circuit.

With a remote control constructed as I have described it may readily be seen that signals may be heterodyned into a receiver, from a point distant from the receiver within the range of the connecting cable which may be as long as 60 feet without affecting the operation of other local receivers. It may also be seen from the foregoing disclosure that numerous other oscillators might be connected to a receiver to operate the receiver from different points.

With such an installation, a local receiver could be installed in an out of the way or a hidden place with reproducers built into the walls, and various controls disposed at various convenient points.

Although I have not specifically illustrated a power line switch for the remote control, the same might be readily incorporated in the present control with but the addition of one or two wires.

Having thus described my invention I am aware that numerous and extensive departures may be made therefrom but without departing from the scope of the invention.

I claim:

l. In a heterodyne radio receiver, a first detector stage, means for tuning said first stage resonant to an incoming signal, an oscillator coupled to said first stage for generating a sine wave adapted to be mixed with the incoming wave to provide a beat frequency wave, an intermediate frequency amplifier resonant to the beat frequency wave, a detector for rectifying the signal, an audio frequency amplifier to amplify the output of the detector, and means to convert the signal to audibility, a second oscillator coupled to said first stage, means to convert said first tuned stage to a substantially aperiodic stage and simultaneously switch-out the first oscillator and switchein the second oscillator whereby the set may be controlled from a remote point by the second oscillator'.

2. In a radio receiver of the heterodyne type including an antenna coupler comprising primary and secondary inductances, a variable capacity for tuning the secondary inductance a first detector coupled to the said secondary inductance, an oscillator inductively coupled in the secondary, for providing a beat note with an incoming signal, an intermediate radio-frequency amplifier, a detector for demodulating the beat note signal, an audio frequency amplifier and a loud speaker, a second-oscillator dependable and remotely coupled to said receiver, a resistance adapted to be bi-passed around said tuning means for the secondary inductance to render the capacity ineffective and cause the inductance to be responsive to the entire broadcast range,

means for coupling it to the input circuit of the y first stage and means for energizing and de-energizing said oscillator, said first stage and oscillator adapted to heterodyne received signals of various frequencies to the intermediate frequency amplier, a detector for demodulating H said heterodyned signals, an audio frequency amplifier for amplifying the demodulated signals and a reproducer to render audible the amplified signals; an auxiliary portable oscillator having means for coupling it to the input circuit of the first stage and means for energizing and de-energizing the same, said oscillator adapted to be directly connected to said first stage, a resistance adapted to be coupled across the tuning means for the first stage, switch means to de-energize said local oscillator and energize said portable oscillator, and connect said resistance across the tuning means of the first stage to render said first stage aperiodic.

4. In a radio receiver of the heterodyne type, comprising a first stage having a tuning means therefor, a local oscillator and an intermediate frequency amplifier, said local oscillator having means for coupling it to the input circuit of the rst stage and adapted to generate an oscillatory wave of selected frequency, and means for energizing and de-energizing the same, said generated frequency adapted to be combined with an incoming signal of known frequency and heterodyned to the intermediate frequency amplifier, a detector for demodulating said amplified heterodyne signals, an audio frequency amplier for amplifying said demodulated signals and a reproducer to render audible said amplified signals, an auxiliary portable oscillator for coupling it to the input circuit of said first stage and means for energizing and de-energizing the same, a resistance adapted to be connected across the tuning means for the first stage,

switch means to de-energize said local oscillator i.

and energize said portable oscillator and to connect said resistance across the tuning means of the first stage to render the first stage aperiodic, tuning means to tune the portable oscillator for heterodyning a selected signal to the intermediate frequency amplifier.

CHESTER E. BRUSH.

having means y 

